Prefetch @import files from CSS files.

Source/core/html/HTMLLinkElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Rob Buis (rwlbuis@gmail.com)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 26 matching lines @@
 #include "core/events/Event.h"
 #include "core/events/EventSender.h"
 #include "core/dom/StyleEngine.h"
 #include "core/fetch/CSSStyleSheetResource.h"
 #include "core/fetch/FetchRequest.h"
 #include "core/fetch/ResourceFetcher.h"
 #include "core/frame/ContentSecurityPolicy.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/LocalFrame.h"
 #include "core/html/imports/LinkImport.h"
+#include "core/html/parser/CSSPreloadScanner.h"
 #include "core/loader/FrameLoader.h"
 #include "core/loader/FrameLoaderClient.h"
+#include "platform/text/SegmentedString.h"
 #include "wtf/StdLibExtras.h"
 
 namespace WebCore {
 
 using namespace HTMLNames;
 
 static LinkEventSender& linkLoadEventSender()
 {
     DEFINE_STATIC_LOCAL(LinkEventSender, sharedLoadEventSender, (EventTypeNames::load));
     return sharedLoadEventSender;
@@ skipping 303 matching lines @@
     return adoptPtr(new LinkStyle(owner));
 }
 
 LinkStyle::LinkStyle(HTMLLinkElement* owner)
     : LinkResource(owner)
     , m_disabledState(Unset)
     , m_pendingSheetType(None)
     , m_loading(false)
     , m_firedLoad(false)
     , m_loadedSheet(false)
+    , m_isPreloadScanning(true)
 {
 }
 
 LinkStyle::~LinkStyle()
 {
     if (m_sheet)
         m_sheet->clearOwnerNode();
 }
 
 Document& LinkStyle::document()
@@ skipping 39 matching lines @@
     styleSheet->parseAuthorStyleSheet(cachedStyleSheet, m_owner->document().securityOrigin());
 
     m_loading = false;
     styleSheet->notifyLoadedSheet(cachedStyleSheet);
     styleSheet->checkLoaded();
 
     if (styleSheet->isCacheable())
         const_cast<CSSStyleSheetResource*>(cachedStyleSheet)->saveParsedStyleSheet(styleSheet);
 }
 
+void LinkStyle::dataReceived(const CSSStyleSheetResource* cachedStyleSheet, const char* data, int length)
+{
+    if (m_isPreloadScanning) {
+        m_isPreloadScanning = false;

[abarth-chromium, 2014/03/05 00:27:35]

Why do we only scan the first chunk?  What if |length| is 1?  It seems better to
scan until we've reached some state in the preload scanner..

+        CSSPreloadScanner m_preloadScanner;
+        PreloadRequestStream pendingPreloads;
+        m_preloadScanner.scan(data, SegmentedString(data), pendingPreloads);
+
+        HTMLResourcePreloader m_preloader(&document());
+        m_preloader.takeAndPreload(pendingPreloads);
+    }
+}
+
 bool LinkStyle::sheetLoaded()
 {
     if (!styleSheetIsLoading()) {
         removePendingSheet();
         return true;
     }
     return false;
 }
 
 void LinkStyle::notifyLoadedSheetAndAllCriticalSubresources(bool errorOccurred)
@@ skipping 185 matching lines @@
 void LinkStyle::ownerRemoved()
 {
     if (m_sheet)
         clearSheet();
 
     if (styleSheetIsLoading())
         removePendingSheet(RemovePendingSheetNotifyLater);
 }
 
 } // namespace WebCore